I have read an article from Xamarin, and came across a particular computer science word : Ahead of Time.
According to some google search result, this AOT does not allow for code generation during run time.
Does it mean, it does not support dynamic stuff?
I know this question may stupid and I have 0 knowledge in IOS, hopefully can get some answer from here. thanks
First, what is the definition of dynamic? For the general public, dynamic code mean the application can change functionality at run-time. For the iOS platform, the binaries are signed to prevent malware. And Apple don't like apps that can load functionality at run-time.
An ahead-of-time (AOT) compiler has nothing to do with dynamic code per se. It's has to do with intermediate language that are just-in-time compilation (JIT). The biggest example of intermediate language is Java bytecode; compile once, run anywhere. When a Java application is executing, the compiled code is JIT to native machine code. AOT compiler is just doing it ahead of time, to save time.
For the iOS platform, Xcode compiles Objective-C to a native binary for the device.
Another way of looking at this is with an example...
In .Net, you can use the Reflection.Emit namespace to generate and compile code at runtime.
Eg you could create an "IDE" with a textbox that accepts C#. When you click a button that C# could be compiled by the .Net framework into a custom library that's loaded dynamically or a fully-fledged executable which is launched as a new process.
This is insanely powerful when combined with the rest of the System.Reflection namespace. You can examine objects at runtime and compile custom code based on any criteria you like.
That said... The problems usually outweigh the benefits in most cases. Mainly, it's a massive security issue, especially when running on a consumer device.
It would be possible to create an app that wouldn't have anything close to malicious code, get it audited by apple, then have the app download code from your webserver, compile it, and execute it. This new code wouldn't be audited...
There really is no good reason to be doing this in a consumer app.
Related
Does Dagger2 annotation processor supports the Eclipse incremental compiler?
I setup Dagger2 with the sample app and after a full compile (after cleaning the project) everything works fine, but after small changes (module or component) and only an incremental compiler run nothing is updated (and errors are shown in the Eclipse log).
Is this normal and if not how could I fix this, because full compiler runs are expensive.
Thanks
Yes and no.
Dagger has been written to use only the standard annotation processing API provided as part of the JDK. There is nothing compiler-specific in its implementation. So, theoretically, Dagger should work under any compiler.
Unfortunately, in trying to run Dagger with Eclipse's implementation of that API we have bumped up against a significant number of bugs. Anything based on ECJ (Eclipse's incremental compilation, Android's Jack toolchain, etc.) tends to crash in unexpected ways.
While projects like AutoValue exercise annotation processing in limited enough ways as to build in workarounds for their required functionality, that would be a significantly larger undertaking for Dagger.
So, if/when Eclipse can reliably support annotation processing, Dagger should work.
In this article it says: "The Dart VM reads and executes source code, which means there is no compile step between edit and run.". Does that mean that you can exchange source-code on the fly in a running Dart system like in Erlang? Maybe the compiler is removed from the runtime system and then this is no longer possible. So that's why I'm asking.
Dart is run "natively" only in Dartium, which is a flavour of Chrome with DartVM. When you develop an application you still need to compile it it to JavaScript. This way you get fast development lifecycle and in the end you can compile code to JS. Because it's compiled code there is lots more room for compiler to run optimisations on the code. So from my perspective, the compiler is still there and I don't think you would be able to replace code at runtime.
You can send around source code and run it, but it would need to be in a separate isolate. Isolates do have some relationship to Erlang concepts.
The Dart VM doesn't support hot swapping (Called live edit in V8). However, based on mailing list discussions, it sounds like this is something that the authors do want to support in the future.
However, as the others have mentioned, it is possible to dynamically load code into another isolate.
Is there any migration analysers available for MonoTouch ?
I have seen one for Mono, but not for MonoTouch.
Short answer: No, there is none at the moment.
Long answer
The situation is a bit different from Mono. In general you test a complete and compiled (against a specific version of the framework) .NET application with MoMA, to get a report of what pieces are missing (or incomplete) in Mono that could affect the execution of your application on other platforms (e.g. OSX and Linux).
Testing a complete applications for MonoTouch would reports tons of issues - since the UI toolkit is totally different. E.g. anything about System.Windows.Forms, WPF... would always missing.
However if your assemblies are already split into (something like) an MVC design it would be possible to test some (the non-UI parts) of them against definitions based on the MonoTouch base class library.
Finally if someone has an immediate need (or looking for a nice project) MoMA is available as open source and the evaluation versions of MonoTouch contains all the assemblies needed to build the definitions files. A bit of extra filtering could make this into a very nice tool.
Alternative
You can see a list of the assemblies that are part of MonoTouch and some platform restrictions (compared to .NET) you should be aware.
I am having a Graphics application using GL API written in c++ and using openGL compiler to compile it.
i am looking ways how can i profile the application along with compiler ( i am having access to compiler code too which i can change for my usage and is in C++).
i am mainly looking for ways i can profile related to compilation , how much time it was taken by compiler functions while compiling C++ application.
i had tried using timer API but if there is some profiling tool like gprof in android which i can use it will be easy for me.
i read about Traveview but i think its meant for mainly java application.
any suggestion will be highly use to me.
If you want to make your app run faster, and you have source code and can run it under a debugger, you can use this technique.
If you want the compiler to run faster, and you have source code and can run it under a debugger, you can use the same technique.
If you had gprof, you could use it, but you would be disappointed, for these reasons.
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Any way to use some Scala for iOS coding?
Would it be possible to use the Scala.NET implementation, and then MonoTouch to run Scala code on an iOS device?
I have not been able to find a page with binaries of Scala.NET that I can test, so the following are just general guidelines as to what you can do with MonoTouch and .NET languages.
MonoTouch can run any ECMA CIL that you feed to it. When you consider using a new language with Monotouch, there are two components that come into play:
Tooling for the IDE
Runtime for the language
The tooling for the IDE is the part responsible for starting the builds, providing intellisense and if you use Interface Builder, it creates a set of helper methods and properties to access the various outlets in your UI. As of today, we have only done the full implementation for C#. What this means for an arbitrary language is that you wont get the full integrated experience until someone does the work to integrate other languages.
This is not as bad as it sound, it just means that you need to give up on using XIB files from your language and you probably wont get syntax highlighting and intellisense. But if you are porting code from another language, you probably dont need it. This also means that you would probably have to build your assembly independently and just reference that from your C# project.
So you compile with FoobarCompiler your code into a .dll and then reference in your main C# project.
The language runtime component only matters for languages that generate calls into a set of supporting routines at runtime and those routines are not part of the base class libraries (BCL). C# makes a few of those calls, but they are part of the BCL.
If your compiler generates calls to a supporting runtime that is not part of the BCL, you need to rebuild your compiler runtime using the Mono Mobile Profile. This is required since most runtimes target a desktop edition of the BCL. There are many other API profiles available, like Silverlight, Mono Mobile, Compact Framework and Micro Framework.
Once you have your runtime compiled with our core assemblies, then you are done
If you had read the MonoTouch FAQ, you would have noticed that it currently supports only C# and no other CLR languages.
Binaries for the Scala.NET library and the compiler can be obtained via SVN, in the bin folder of the preview:
svn co http://lampsvn.epfl.ch/svn-repos/scala/scala-experimental/trunk/bootstrap
Bootstrapping has been an important step, and ongoing work will add support for missing features (CLR generics, etc). All that will be done.
For now we're testing Scala.NET on Microsoft implementations only, but we would like our compiler to be useful for as many profiles and runtime implementations as possible.
A survivor's report on using Scala.NET on XNA at http://www.srtsolutions.com/tag/scala
Miguel Garcia
http://lamp.epfl.ch/~magarcia/ScalaNET/